As is known in the art, chewing gum compositions include a number of ingredients, some of which are subject to deterioration through oxidation during storage. Mint oils are important ingredients of chewing gum which require stabilization, both before and after the mint oils are incorporated into the chewing gum. The term "mint oil" as used herein includes, but is not limited to, peppermint oil, spearmint oil, corn mint oil and Scotch spearmint oil. The use of peppermint oil in chewing gum, enhanced with a minor amount of spearmint oil, is discussed in U.S. Pat. No. 4,948,595 issued to Patel et al.
Several synthetic antioxidants are in widespread use for stabilizing mint oil and mint flavored chewing gum compositions. Among the most notable of these synthetic antioxidants are Butylated Hydroxy. anisole (BHA), Butylated Hydroxytoluene (BHT) and tertiary butyl hydroquinone (TBHQ). While BHA, BHT and TBHQ are effective in preventing and reducing oxidation of mint oil and mint flavored chewing gum compositions, these compounds have been found to be carcinogenic in animal testing.
Tocopherols are naturally occurring compounds which are known to have antioxidant properties. The most common tocopherol, alpha-tocopherol, is also known as vitamin E. The other common homologs are beta, gamma and delta tocopherols. All of these tocopherol homologs are FDA approved additives which have been shown to be safe in animal testing. Natural tocopherols are usually derived from vegetable oils, especially soybean oil. Tocopherols can also be found in many spices, fruits, nuts, seeds and other plant sources.
Unfortunately, tocopherols have been found to be generally less effective than BHA and BHT in preventing oxidation of mint oil and mint flavored chewing gum. Tocopherols also have upper usage level limits, above which oxidation of the mint oil will start to increase again. Tocopherols have been used successfully as chewing gum stabilizers when added in combination with certain synthetic stabilizers. U.S. Pat. No. 4,489,099 issued to Shaheen et al. discloses the use of vitamin E tocopherol in combination with dilauryl thiodipropionate (DLTDP). However, it has previously been less effective to use tocopherols in mint oil, or in mint flavored (or other) chewing gum compositions, by themselves.